Supercritical fluid extraction of cobalt

Abstract

Cosolvated supercritical fluid carbon dioxide has been investigated for its potential for the kinetically controlled extraction of coordinated cobalt ions with 2-ethyl hexyl 2-ethyl hexyl phosphonic acid as the -complexing agent. Hexamine has been used as the coordinating agent and heptane as the cosolvent. A mixture of cobaltous chloride and hexamine with a small quantity of water was made to react dynamically with the complexing agent in heptane in the medium of supercritical fluid carbon dioxide (SCF CO₂) . Extraction efficiencies have been found as a function of time and the optimum pressure temperature regime established. The study has implications for the end purification of cobalt from nickel and may serve as a role model for the refining and purification of one rare earth element from its other rare earth impurities.